Transformer



United States Patent TRANSFORNIER Wolfgang Dittrich, Grossauheim, Hessen, and Martin Krause, Dresden, Germany, assignors to VEB Elektroschaltgerate Grimma, Grimma Saxonia, Germany Filed June 3, 1957, Ser. No. 663,281 7 4 Claims. (Cl. 33'6135) This invention relates to transformers, and more particularly has reference to a transformer of the type in which changes in the resistance of the magnetic circuit may be obtained.

Heretofore, it has been known to provide current transformers capable of regulation, through the medium of varying an air gap defined by the movable transformer legs. In such instances, the gap is capable of adjustment through the medium of a device which is adapted to move the parts of the transformer about a supporting point, so that changes in the resistance of the magnetic circuit may be obtained. A transformer of this type may be found, for example, in West German Patent No. 843,871.

It is also known to provide tarnsformers having a variable secondary voltage and an iron core with three legs, in which transformers the air gap formed between the three legs is varied through the medium of a magnetic controller.

The present invention, summarized broadly, has reference to transformers in which the transformation ratio is capable of adjustment by varying an air gap through the medium of a magnetic adjusting member. In this connection, it is proposed in carrying out the invention to provide a transformer that is of markedly simple construction, and in which a greater, sensitive range of adjustment is obtained. In obtaining such range it is proposed, in carrying out the invention, to provide a laminated yoke turntable as the adjusting member in a plane normal to the general plane of the transformer legs, while maintaining at all times a constant distance between the transformer legs.

In this connection, the greater sensitivity of the adjustment results from the air gaps, arranged one behind the other between the plates of the adjusting member, which participate in the rotating action. Also, the transformation ratio can be greatly extended, almost to any range desired, through the provision in the yoke of one or more non-ferromagnetic layers of any desired thickness and any desired spacing from one another.

A further object of the invention is to provide a transformer of the character described which will be adapted to produce the highly desirable results noted above, while still being capable of manufacture at little or no increase in cost above that required for transformers not having the advantages of the invention.

Yet another object of importance is to provide a transformer as described in which the adjustments desired can be effected swiftly and easily, and without loss of efliciency in the transformer in any position to which it is adjusted.

For other objects and a better understanding of the invention, reference may be had to the following detailed description taken in connection with the accompanying drawing in which:

Fig. 1 is a perspective view of a variable transformer according to the present invention;

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Fig. 2 is a perspective view in which the yoke has been adjusted from its Fig. 1 position; and

Fig. 3 is a perspective view in which the yoke has been adjusted still further, to provide yet another adjustment.

Referring now more in detail to the drawing, 1 designates a magnetic body, provided with primary and secondary windings 2., 6 respectively. The body is approximately U-shaped, and the legs thereof are bridged by a yoke or armature 3, having a non-ferromagnetic layer 4, said yoke being rotatably supported upon the legs, with a fixed air gap 5 being defined between the yoke and the yoke-contacting surfaces of the legs.

Considering the construction of the body 1 in greater detail, said body is formed of a selected number of flat, U-shaped plates 7, said plates being identically formed with their edges in registration and being individually of a U-shape, so as to form the body to a U-shape when the plates are assembled and fixedly connected through the medium of connecting elements 8 extending through registering openings of the several plates 7. The plates are, of course, in face-to-face contact, in parallel planes and when connected, provide upon the body 1 upwardly projecting, thick legs 9, 10 of body 1. The primary and secondary windings are coiled about the legs 9, 10.

The yoke comprises a plurality of like plates 11, there being an equal number of the plates 11 at each side of the layer 4. Plates 11 are connected by fastening elements 12.

The yoke 3 is used as a control member, to vary the effective air gap, which consists of the fixed air gap 5 and the plate insulating layer acting as an air gap and lying to a greater or lesser extent in series with the same. The yoke 3 is turnable in its own plane, that is, the yoke rotates in the general plane of the yoke, which is a fiat body lying upon the upper ends of the legs 9, 10.

In this connection, the yoke rotates in a plane normal to the planes of the plates 7, that is, normal to the lengths of the legs 9, 10, considering said lengths in the direction of extension of said legs upwardly from the bight portion of the body 1.

As a result, the yoke necessarily is rotatably adjustable at an angle to the direction of the layer, and the transformation ratio is thus continuously variable, by reason of variation of the magnetic resistance of the circuit. said variation of course is effected through the provision of a laminated yoke, turnable as the adjustment member in a plane at right angles to the planes of the plates 7, while at all times the spacing of the yoke is maintained at a constant value in respect to the distance of the yoke from the transformer legs 9, 16.

A further important characteristic of the invention resides in the fact that in the yoke or adjustment member, one or more non-ferromagnetic layers of any desired thickness and spacing from each other can be provided, in a manner such as to extend the transformation ratio.

While various changes may be made in the detail construction, it shall be understood that such changes shall be within the spirit and scope of the present invention as defined by the appended claims.

What we claim as new and desire to protect by Letters Patent of the United States is:

1. A variable transformer comprising a magnetic core having two spaced legs having ends terminating in a common plane, said core including a plurality of magnetic laminations in face-to-face contact in parallel planes, primary and secondary windings coiled about said legs, and an armature rotatably mounted in spaced juxtaposition to said ends of said core legs for rotation in a plane which is parallel to the ends of said core legs, said armature continuously bridging said core legs during its rotation, the armature comprising laminations extending perpendicularly to the plane of rotation.

2. A transformer according to claim 1, wherein said armature includes a non-magnetic layer separating the laminations of said armature.

3. A transformer according to claim 1, wherein said armature is rotatable through an angular distance of at least 90.

4. A transformer comprising a generally U-shaped magnetic core including two upwardly projecting legs having coplaner flat top surfaces, primary and secondary windings coiled about the respective core legs, and a fiat armature formed of magnetic laminations lying in planes perpendicular to said top surfaces, said armature being rotatably supported at a constant distance above the top surfaces of said core legs and continuously bridging said core legs, said armature being rotatable about an axis intermediate said legs and normal to the plane of said top surfaces of the core legs.

References Cited in the file of this patent UNITED STATES PATENTS 2,145,742 Wechsung Jan. 31, 1939 2,484,022 Esval Oct. 11, 1949 2,602,097 Muller July 1, 1952 10 2,730,664 Karlson Jan. 10, 1956 FOREIGN PATENTS 757,247 France Oct. 9, 1933 969,415 France May 24, 1950 

